Children with increased but "subtoxic" lead exposure appear to be at increased risk of cognitive and perceptual dysfunction, and lowered scores on individually administered neuropsychologic tests. To assess whether these indicators of dysfunction precede or follow lead exposure, we designed and initiated our Prenatal Lead Exposure Study (which we now call our "intensive" follow up study). We began by measuring the lead level in umbilical cord blood from 11,837 births at one hospital. This enabled us to identify and then follow a total of 249 children divided among the highest lead levels, those with the lowest lead levels, and those whose lead levels approximated the 50th percentile. During the first year these umbilical cord blood specimens were obtained, other investigators (conducting a separate study) interviewed all of these women about demographic, lifestyle, and pregnancy characteristics. These 4,354 children, whose umbilical cord blood lead level has been measured, and whose mothers were interviewed at the time of delivery are viewed as a unique resource for a study of the relationships between pre- and postnatal lead exposure and dysfunction at school age. Children born to most of these women have received birthday cards from us at ages 3, 4 and 5 years. This proposal requests funds to enable us to continue to follow these children, collecting a deciduous tooth from each (in order to estimate cumulative postnatal lead exposure), and to collect an updated questionnaire from the mother, and a performance-in-school questionnaire from each child's teacher at the end of the school year in which the child is 8 years old. Collecting these additional data from this unique sample will allow us to achieve the two aims of A) determining the relative contributions of exposures to lead prenatally and postnatally to behavioral, cognitive, and perceptual dysfunction recognized by teachers when the children are aged 8 years, and B) determining the umbilical cord blood and tooth lead levels associated with dysfunction in school at that age. This study has been designed to complement the "intensive" follow up study of the 249 babies selected from this same sample.